Tourniquet cuffs are wrapped around the limb of a living being in order to keep blood out of the limb and/or to keep local anesthesia from escaping the limb. The cuffs are used for many different medical procedures performed on the limb such as orthopaedic surgeries to name one example. The conventional inflatable tourniquet cuffs are snuggly wrapped around the limb and secured by pressing a hook or loop type material surface such as VELCRO® on the free end of the cuff to a mating hook-loop type material surface along the body of the cuff. Inflatable cuffs have at least one fluid-tight bladder and one or more ports that extend from the bladder and out of the cuff. The ports are connected to tubes that are in turn connected to an air-supplying tourniquet machine. The air volume and pressure for inflating the cuff is then controlled at the tourniquet machine. The inflated cuff applies a force against the limb that is sufficient to occlude the arteries and veins extending through the limb to stop arterial blood flow to the limb and venous blood flow and anesthesia from flowing out of the limb.
When the cuff is first wrapped around the limb while the cuff is deflated, ideally the cuff should be secured so that the cuff is not too loose and not too tight. A cuff that is properly tightened on the limb will form a defined cylinder with spiraling layers. A cuff that is too loose, however, may “telescope” out of the cylindrical shape during use and along the patient's limb. This can cause a partial or total loss of occlusion of the arteries and veins.
On the other hand, a cuff that is too tight can cause venous occlusion even though the cuff is not inflated. Pre-surgery, venous occlusion can cause poor exsanguination such that a sufficient amount of blood cannot exit the limb due to the tight cuff. This can occur while using gravity exsanguination where the limb is elevated for a particular amount of time and/or while using tensors such as wraps or other elastic bandages used to squeeze the blood out of the limb.
Post-surgery, venous occlusion by a deflated cuff can form a venous tourniquet which means that the blood engorges the limb and pools in the limb because the veins are partially or fully occluded while the arteries are still bringing blood to the limb. This may cause a dangerous deep vein thrombosis (DVT) otherwise known as a blood clot. This can occur when a surgical team deflates the cuff but leaves the cuff applied to the limb while the surgical team performs other final procedures such as closing the wound, placing drains or catheters in or near the surgical site or checking range of motion of the implant. The surgical team may not notice that the cuff on the limb is too tight and is causing a venous tourniquet because the cuff applied on the limb is often covered by surgical drapes, bandages, distal seals and/or soft tissue protection layers used between the cuff and the limb which may extend beyond the cuff on the limb such as stockinettes, sleeves, cotton cast padding, or sheet padding.
A “1-2-3 finger” test or rule is known for determining if the deflated cuff was wrapped around the limb with the correct amount of tightness or pressure. For this rule, after the cuff is wrapped around the limb, the fit is checked by attempting to put one finger between the limb and the applied cuff If one finger does not “fit”, or is too tight, the cuff is applied too tight. If two fingers fit comfortably between the cuff and the limb but not too tightly, the cuff is applied properly. If three fingers fit between the cuff and the limb, the cuff is too loose. However, a more objective way is desired for determining whether or not a tourniquet is applied to a limb with the proper amount of force.